Preheat the oven to 350°F. Grease and line an 8×8 or 9×9 baking dish with parchment paper and set aside.
In a saucepan, melt the butter over low-medium heat. Add in sugar slowly and whisk continuously (this step is very important as it helps melt the sugar, which will give the brownies a the flakey crackly crust on the top).
Continue whisking for approx 1-2 minutes after all the sugar has dissolved.
Transfer the butter mixture over to a large bowl and let cool slightly. Add in eggs one at a time, whisking vigorously between each egg, then add the vanilla.
In a separate bowl, sift the cocoa powder, gluten free flour, baking powder and salt.
Add dry ingredients to wet ingredients and mix until just combined. Transfer the brownie batter over to the prepared pan and top with chocolate chips, cacao nibs, or chopped nuts if you desire.
Bake for 25-30 minutes in preheated oven, ensuring you do not over bake.
Remove from the oven and cool for about 15 minutes. Cut in half then cut in alternating diagonals into triangle shapes, as in the photo shown above in this blog post.
Spoon the red icing into one zip lock bag or piping bag and the white icing into another.
Seal the bags and cut off a small corner with scissors.
Squeeze out the icing in a curvy zigzag as you fill the center with red icing. Finish the bottom and top off with white icing as pictured.
Enjoy your new favorite holiday sweet treat!